Stars form from gas and dust in vast clouds in spiral galaxies. We see these starforming regions relatively nearby in our own Milky Way, and in distant galaxies, so their apparent size varies tremendously, but their true size varies as well, depending on the mass of material and other physical properties. This graphic compares four prominent starforming regions at the same spatial scale, that is, as we would see them if they were all at the same distance. The Tarantula Nebula (30 Doradus) in our galactic neighbor the Large Magellanic Cloud, is one of the largest starforming regions known, much larger than any in the Milky Way, such as the relatively nearby Orion Nebula, more distant Carina Nebula or Gum 29 (Westerlund 2). Star-forming Region Size Comparison courtesy of Z. Levay (STScI)